Usage:
953C (2ZN) Track-Type Loaders
Reference: Service Manual Module; SENR5664; "Air Conditioning and Heating Systems With R-134a Refrigerant".
Reference: Service Magazine; SEPD0424; July 6, 1998; Page 13; "New Components Increase Heater Group Service Life".
Description of Change: Several areas exist in the air conditioning and heating systems where contamination of these systems can occur. Sealing around the return air and fresh air filter assemblies, water valve control cable binding, heater coil and control valve leakage, condensate drainage, frozen evaporator coil, and compressor mounting bracket fatigue are a few of the areas that the following update procedures will help to eliminate.
Adaptable To: The heating and air conditioning updates are adaptable to 953C (2ZN1-1749) Track-Type Loaders.
Removal of Heater And Evaporator Components
A new condensate drainage system is being added. Two drainage holes are provided in the new basin instead of just one, as in the current basin. The location of the drains and the drain tube routing are improved as a result.
Recover the refrigerant from the air conditioning system using an EPA approved recovery station and following the manufacturers instructions for the unit. Measure the amount of oil that was recovered with the refrigerant and record both the amounts of refrigerant and oil for later use. Note: It is important that the recovery station be capable of measuring the amount of oil that is removed from the system along with the refrigerant.
Stop the flow of water to the heater coil by closing two shutoff valves (1) and (2) located in the engine compartment.
Remove engine enclosure support (3) on the right side of the machine.
Remove plate (4) that covers the heater/evaporator enclosure.
Disconnect two lines (5) and (6) from the heater coil and plug the hoses.
Disconnect two lines (7) and (8) from the refrigerant coils and cap the lines.
Remove the operators seat.
Remove return air filter panel (9) and heater/evaporator compartment access panel (10).
Remove two hoses (11) and cap the lines.
Remove thermostat probe (12) from the evaporator coil.
Disconnect two wiring harnesses (14) and (15). Also, disconnect the water valve cable. The water valve cable may be cut to ease removal, as the cable is going to be replaced at a later time.
Remove cover (13) to expose the two coils. Move the cover aside, as the components on the cover will need to be transferred to the new cover at a later time.
Remove two bolts (16) that hold the two coils in place. Pull the two coils out of the assembly and discard them appropriately.
Disconnect drain tube (17) from the condensate drain basin and discard the tube.
Remove condensate drain basin (18) from the heater/evaporator coil compartment and discard the basin.
With the heater/evaporator coil now removed, clean the compartment in order to avoid contamination of the new components when they are installed.
Preparation Of The Compartment For Installation Of The New Components
Prior to installing the new components, seal the areas shown in the previous illustrations with 5P-7070 Insulation Tape.
(A) (B) (C)
Locate the plate assembly that the former condensate drain pan was resting on. Locate the centers of the two 30.0 mm (1.18 in) holes on the plate.
The top portion (lip) of the sheet metal must be removed. Grind to the spot welds and remove the top portion (lip) of the sheet metal.
Drill or punch the two holes through the sheet metal.
The original 22.0 mm (.87 in) drain pan hole in the center of the plate should be covered by welding a scrap piece of sheet metal over the hole. Weld the piece in place to permanently seal the hole and pain the piece to prevent corrosion.
Installation Of New Condensate Drainage Basin
(19) 3E-6753 Grommet
Place one grommet (19) into each of the two 30.0 mm (1.18 in) holes.
Apply 4C-9612 RTV Sealant liberally to the top of each grommet. Install a new 155-0154 Basin through the holes.
Cut the appropriate length of condensate drain hose from a length of 5P-6129 Bulk Hose. There must be enough hose to route as shown above. The hose should not have any kinks and should always direct the flow downward. Also, the hose should not rest in the bottom guards of the machine.
Attach the two drain hoses to the two nipples on the bottom of the condensate drain basin where the nipples protrude through the bottom of the sheet metal plate.
Secure the two drain hoses to the drain basin with the 1P-4278 Clamps.
Tie the hoses down at the appropriate locations using the three 3S-2093 Straps.
Insert one 7T-9793 Valve into the open end of each drain hose. Verify that the valve is inserted into the hose in the correct manner.
NOTE: If the above step is not performed, condensate water will not drain properly from the basin and contamination of the air conditioning system could occur.
Installation of New Heater Group
A new heater coil and water valve assembly are being added to prevent coolant leakage due to poor sealing interfaces.
A new 139-6908 Heater Coil and 139-8653 Valve Assembly should be installed using the items listed in the referenced Service Magazine article.
Install a new 153-6271 Control in place of the existing control (shown from below). The new cable is more resistant to contamination and should improve binding and sticking issues.
Open two shutoff valves (1) and (2) located in the engine compartment.
Start the engine and turn the control knob in the cab to full heat. Check for leaks where the hoses connect to the new heater coil. Verify that the new control cable allows full travel of the water valve to both the ON and OFF positions. Adjust the cable as required by loosening and tightening the clip on the water valve where the cable is secured.
Installation Of New Evaporator Coil And Related Components
The new 155-2005 Coil is a larger 4-Row design compared to the former 128-1201 Coil and offers improved cooling capacity for the air conditioning system.
Prior to installation, the exposed tube surfaces on the new coil should be insulated using generous amounts of 5P-7070 Insulation Tape. This will prevent water droplet formation on the cold tube surfaces that could lead to spillage of water into the cab. Note: Do not remove the plugs from the new evaporator coil until you are ready to make the refrigerant line connections. An evaporator coil that is received without plugs in the fittings should be rejected and returned.
Install the 155-2005 Coil by securing it to the bracket inside the compartment that lines up with the mounting holes. The heater coil is also secured to this bracket through common holes that line up with those on the evaporator coil. Both coils are mounted using two 8T-4200 Bolts and two 8T-4224 Washers.
Relocate the 8.0 mm (.32 in) hole in the 155-0155 Plate Assembly as shown. The hole is for insertion of the thermostat probe into the evaporator coil. Cover the old hole with a piece of 5P-7070 Insulation Tape.
Transfer all components from the former top cover to the new 155-0155 Plate Assembly.
Once the new hole has been created in the plate, establish a matching hole on the 155-0156 Seal. It is not necessary to cover the old hole in the seal. Lay the seal across the coil assembly and then cover with the new plate assembly.
Bolt the new plate and seal into place using the fasteners that were removed from the former plate assembly.
With the exception of the last 140.0 mm (5.51 in), cover the thermostat probe with 3E-9553 Tubing. Very precisely, insert the thermostat probe through the 8.0 mm (0.32 in) hole in the 155-0155 Plate Assembly into the evaporator coil to a depth of 140.0 mm (5.51 in) in order to provide acceptable freeze control for the air conditioning system.
Connect the refrigerant lines to the two new coils. Use new 9X-7381 and 9X-7382 O-rings on the refrigerant lines. Be sure to place a few drops of clean refrigerant oil on the O-rings before assembly in order to help sealing and avoid damage. Tighten the refrigerant lines to a torque of 65.0 ± 6.0 N·m (47.79 ± 4.41 lb ft), using a backing wrench so that the coil tubes do not twist.
Replace the inline dryer. Remove the plastic trim panel on the right rear cab post to expose the 3E-3535 Dryer. Remove the old dryer and discard the dryer. Check the condition of the 103-6100 Fittings for excessive wear. Replace the fittings, as required. If the fittings are replaced, be sure to use new 9X-7380 O-ring seals at each connection and also coat the seals with a few drops of refrigerant oil.
Procedure To Check For Proper Slack In Routing Of Air Conditioning Lines To Compressor
Loosen the compressor bolts so that the compressor can rotate freely. Remove the belt from the compressor pulley.
Move the compressor out to the position where there would normally be maximum belt tension. Verify that there is still slack available to the refrigerant lines. If slack is not present, adjust the lines, which could involve reclipping the lines to different locations.
If it becomes necessary to loosen the compressor block fitting so that the lines may be rotated, be sure to replace each of the 9X-7385 O-ring seals and lubricate the seals with refrigerant oil.
Clamp the block fitting bolt to 25 ± 7 N·m (18.4 ± 5.1 lb ft) when putting the assembly back together.
Recharging The Air Conditioning System
Recall the amount of oil that was removed from the air conditioning system during the refrigerant recovery process. Fill the refrigerant compressor with new 4C-2959 PAG oil in the amount that was recorded earlier after the recovery process.
NOTE: Be sure to seal the PAG oil container when not in use, as PAG oil can become contaminated by absorbing moisture from the ambient surroundings.
The oil can be poured directly into the compressor by removing the oil fill plug located on the compressor crankcase.
NOTE: Always use a thoroughly clean measuring device to pour oil into the compressor in order to prevent contamination of the air conditioning system.
In some cases, the air conditioning charging equipment may come with a device that charges a measured quantity of oil into the air conditioning system. If this is the case, follow the operating instructions that pertain to the specific charging station.
Perform the evacuation and refrigerant charging process as outlined in the referenced service manual module. Once all the evacuation equipment is connected to the air conditioning system, be sure to draw vacuum on the air conditioning system for 90 minutes to ensure that all the air and moisture are extracted.
NOTE: Verify that the refrigerant charging hoses are part of the vacuum so that air is not trapped and thus introduced to the vehicle air conditioning system during the refrigerant charging process.
After the evacuation process is complete, be sure to perform the leak tests, as outlined in the referenced service manual module. The panels that gain access to the evaporator coil should still be off at this point to allow for leak testing the refrigerant line connections inside the compartment. If no leaks are present, charge the air conditioning system with 1.4 kg (3.08 lb) of R-134a refrigerant according to Caterpillar procedures.
NOTE: Make sure to use an accurate charging scale and to charge the system by WEIGHT, not by the pressure gauge reading.
After the charging process is complete, remove the refrigerant tag from inside the cab and replace the tag with a new 110-6393 Plate that has been stamped with the correct refrigerant charge.
Install all covers and access panels except the 126-2636 Filter Cover for the return air.
Improved Sealing Of Return Air Filter Panel
Remove the existing seals on the cover assembly and scrape the sheet metal contacting surface clean of debris as well.
Add seal (C) and seal (D), as shown. Trim seal (C) so that the seal extends past the bottom of the panel slightly in order to prevent a leakage path where the seal joins up with seal (D).
Add seal (E) to the cover assembly around the perimeter of the filter cut-out, as shown. This will increase compression of the rubber on the return air filter and improve sealing.
Check the condition of the original foam rubber seal that remains on the 126-2636 Cover and replace as required.
Before installing the return air filter and cover, seal around the entire compartment in the cab with 4C-9612 RTV Sealant. Apply sealant liberally where air leakage paths can be detected.
Install the 126-2636 Cover and use a light inside the compartment to verify that all leakage paths have been sealed.
Install the 116-7376 Air Filter and retaining cover.
Improved Sealing Of Fresh Air Filter Compartment
Open the cover and remove the fresh air filter.
Shine a light in the compartment, just above where the filter resides. A gap of approximately 3.2 mm (0.13 in) can be noticed around the outer perimeter of the compartment.
Clean the sheet metal surface around the gap with a suitable cleaner. Seal the gap by applying generous amounts of 4C-9612 RTV Sealant into the gap.
Check the condition of the seal on the cover door and replace as required.
Finally, replace the fresh air filter if necessary.
Final Checks
Check the condenser unit on the top of the cab. Verify that both fans are operational and the coil is clean. The coil can be sprayed with water under light pressure to clean the coil, if necessary.
Start the engine and check for proper operation of the air conditioning system. Make a note of air vent temperature, ambient temperature, compressor inlet and outlet pressures and subjective indication of blower airflow when the fan is on HIGH.
Check the above parameters at both LOW IDLE and HIGH IDLE engine speed.
Allow the engine to warm up so that the heater water control valve can be checked for proper sealing when in the CLOSED position.